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**a=[-3,-4,12]**

So I found the follwing:

Let vector

**x**be the unknown vector

**|a|**=13

**|x|**=3

Since they are both in the same direction, they both must have the same direction angles right?

So:

Cos alpha = -3/13 which is equal to a/3

Cos beta = -4/13 which is equal to b/3

Cos gamma = 12/13 which is equal to c/3

Then I got the values for a,b and c but the book shows me a different answer. What am I doing wrong here?